Project Summary Although there has been remarkable progress since the National Academy of Medicine?s report in 2013 describing a path towards Best Care at Lower Cost, we are not where we need to be. My research agenda is to conduct patient-oriented research that advances our understanding of overuse of healthcare among older adults. With the collaboration of junior investigators and other mentees, I will conduct research to understand how health care systems reduce the harmful overuse of healthcare resources by their Medicare beneficiaries through their delivery of high quality primary care. In the last four years of my funded work, my team and I have come to recognize that there is not yet a comprehensive understanding of drivers of overuse at the levels of the patient, clinician, and system, and the most optimal points for interventions are not yet defined. We developed the Johns Hopkins Overuse Index which is an index of 20 procedures that can measure regional variation in the overuse of healthcare resource. The index has been useful as an outcome measure and has allowed us to demonstrate the beneficial impact of higher regional density of primary care doctors on reducing overuse both among Medicare beneficiaries and younger, commercially insured people. I seek to understand the mechanisms by which high quality primary care reduces overuse of resources in older adults through a mixed-methods evaluation of positively deviating health systems and through modeling components of primary care delivery with mediation analysis methods. I also aim to improve the decisions made in the care of older adults by addressing a fundamental problem: that unappreciated heterogeneity of treatment effect (HTE) contributes to overuse of healthcare in older adults. Older adults are at particularly high risk of overuse of healthcare; this is both a discrete subpopulation of all adults, and a population with great variation amongst itself. Contributors to this variation include physiological differences attributable to marked variances in the aging process across individuals that manifests as frailty or robustness, as well as differences that arise due to the degree of multimorbidity, older adults? preferences regarding interventions, and their ability to engage in self-care. The second proposed set of projects will involve the development of methods and tools to help clinicians to communicate more clearly with each other and with patients on this topic. With use of Design Thinking methods and engagement of collaborators from our Department of Art as Applied to Medicine, I will develop a framework and visual tools to assist with clear communication on this topic.